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Home My WebLink About21- Task Order - Tetra Tech - Groundwater & Perimeter Methan Monitoring & Assess. - Landfill FY22 Tetra Tech 851 Bridger Drive, Suite 6; Bozeman, MT 59715 Tel 406.582.8780 Fax 406.582.8790 tetratech.com TASK ORDER 2021 - 2022 GROUNDWATER AND PERIMETER METHANE MONITORING AND ASSESSMENT OF SYSTEM PERFORMANCE AND EFFECTIVENESS BOZEMAN LANDFILL July 14, 2021 CLIENT: CONSULTANT: The City of Bozeman Tetra Tech, Inc. P.O. Box 1230 851 Bridger Drive, Ste 6 Bozeman, Montana 59711-1230 Bozeman, MT 59718 Attention: Mr. Cody Flammond Attention: Mr. Kirk A. Miller INTRODUCTION The purpose of this task order is conduct semi-annual compliance groundwater monitoring and monthly perimeter methane monitoring at the Bozeman Landfill and to conduct detailed evaluations of the performance of the remediation systems and their effect upon groundwater remediation. These activities will be conducted between July 1, 2021 and June 30, 2022 and are directed at meeting DEQ Solid Waste rules and the requirements of DEQ’s June 6, 2014 letter requiring the City of Bozeman to conduct a Corrective Measures Assessment and implement remedial measures. The purpose of the evaluation of the remediation system is to document performance and effectiveness and progress towards meeting groundwater and soil gas remediation goals. The remediation system is comprised of the expanded landfill gas (LFG) collection system, the soil vapor extraction (SVE) system, and the air injection (AI) system. Groundwater monitoring wells were installed, and a groundwater monitoring program was implemented beginning in 1981. Monitoring results have shown that groundwater quality has been impacted primarily by VOCs originating from the Bozeman Landfill’s unlined waste cell. Ten additional monitoring wells were installed during 2014 and two in 2021, which increased the total number of monitoring stations to 35. Monitoring results indicate a southwesterly to westerly groundwater flow. Tetrachloroethene has exceeded regulatory standards in groundwater, on City of Bozeman park property adjacent to the landfill property. Based upon recommendations from the Initial Remediation System Evaluation report (March 9, 2018), two additional groundwater monitoring events are proposed for next year so that quarterly data is available for water quality trending analysis. Hence, September 2021 and March 2022 groundwater monitoring events are proposed to supplement the December 2021 and June 2022 monitoring events, which are conducted for compliance with DEQ’s landfill closure requirements. DocuSign Envelope ID: 7A066529-2DAA-4C73-AA3E-B963C8C31805 Task Order – 2021 to 2022 Groundwater and Methane Monitoring and Assessment Bozeman Landfill, Bozeman, Montana July 14, 2021 Page 2 of 6 TETRA TECH SCOPE OF SERVICES This task order includes the following work activities: • Task 100 - Perimeter Methane Monitoring • Task 200 - Additional Groundwater Monitoring Events • Task 300 - December 2021 Compliance Groundwater Monitoring • Task 400 - June 2022 Compliance Groundwater Monitoring • Task 500 - Evaluate Groundwater Data and LFG System Flow Modification Data • Task 600 - Project Management, Statistical Analysis, and Reporting The scope of work for these tasks are outlined below. Task 100 Perimeter Methane Monitoring Task 1 includes 12 months (from July 2021 through June 2022) of methane monitoring activities. Monitoring is conducted on a monthly basis in eight gas monitoring wells (designated BLG- wells). Gas collected in these wells will be monitored for methane, carbon dioxide and oxygen (with remaining balance as nitrogen) in percent by volume using City of Bozeman’s landfill gas (LFG) analyzer. Monitoring results will be entered into a database and forwarded to City of Bozeman and DEQ - Solid Waste Bureau following each monitoring event. Task 200 Additional Groundwater Monitoring Events - September 2020 and March 2021 Two additional groundwater monitoring events are included in this task order to provide for quarterly data for the year. This data will contribute to the continued assessment of the performance of the remediation system. Groundwater monitoring will be conducted in wells LF-2, LF-3, MW-12, MW-17, MW-18, MW-20, MW-28 and MW-29. The wells will be purged prior to sampling, have field parameters measured (including temperature, pH, specific conductivity, dissolved oxygen, and oxidation reduction potential), and have samples collected for volatile organic compounds (VOCs in accordance with Method 8260 low level). Two quality assurance/quality control (QA/QC) samples will be collected and prepared during this monitoring event. These will be 1) a duplicate sample collected at a monitoring site and submitted for VOCs in accordance with Method 8260 and 2) a trip blank prepared by Pace Analytical Laboratories, shipped with the sample bottles, traveling with sample bottles in the field, and returned to the laboratory for analysis of VOCs. Task 300 December 2021 Compliance Groundwater Monitoring The first groundwater monitoring event contained in this task order will be conducted in December 2021 as part of the routine groundwater monitoring at the Bozeman Landfill. Tetra Tech will perform groundwater monitoring in accordance with Tetra Tech’s Groundwater Monitoring Sampling Analysis Plan. Groundwater monitoring will be conducted in existing groundwater monitoring wells or stations. The scope of the monitoring event will be similar to the typical June monitoring events but will have additional analyses for metals, cations, and nitrogen. A monitoring, sampling, and analysis matrix for the December monitoring event is presented in the Sampling and Analysis Plan (SAP). Tetra Tech requested reductions in the frequency of analysis for some parameters that have not been observed at the landfill in several years, in an effort to reduce costs, hence, this table is modified from previous years. DocuSign Envelope ID: 7A066529-2DAA-4C73-AA3E-B963C8C31805 Task Order – 2021 to 2022 Groundwater and Methane Monitoring and Assessment Bozeman Landfill, Bozeman, Montana July 14, 2021 Page 3 of 6 TETRA TECH Field parameter monitoring and collection of water samples will be conducted in 24 monitoring sites/wells as specified in the SAP. Water levels will be measured in all monitoring wells at the site. Wells will be purged prior to sampling. Field parameters including temperature, pH, and specific conductivity. Field parameters will generally be measured during and at the conclusion of purging the monitoring wells. The field parameters: dissolved oxygen and oxidation reduction potential will be measured if winter weather conditions are at or above freezing. Water samples will be collected and shipped to Pace Analytical Laboratories (in Billings, Montana) for analysis of constituents shown in the SAP. The scope of analysis includes many of the constituents listed in Appendix I, 40 CFR Part 258 (July 1, 2008) in ARM 17.50.1306. The SAP also reflects DEQ approved changes to the monitoring schedule of specified monitoring wells. Five quality assurance/quality control (QA/QC) samples will be collected and prepared during the December 2021 assessment monitoring event. These will include the following: 1) three duplicate samples collected at selected monitoring sites and submitted for analysis of all constituents included in the SAP; 2) two trip blanks prepared by Pace Analytical Laboratories, shipped with the sample bottles, traveling with sample bottles in the field, and returned to the laboratory for analysis of VOCs; and 3) one decontamination blank collected from decontaminated, non-dedicated sampling equipment. Task 400 June 2022 Compliance Groundwater Monitoring A groundwater monitoring event will be conducted in June 2022 as part of the routine groundwater monitoring at the Bozeman Landfill. Tetra Tech will perform groundwater monitoring in accordance with Tetra Tech’s Groundwater Monitoring Sampling Analysis Plan. Groundwater monitoring will be conducted in existing groundwater monitoring wells or stations. A monitoring, sampling, and analysis matrix for the June 2022 monitoring event is presented in the SAP. Field parameter monitoring and collection of water samples will be conducted in 26 monitoring sites/wells as specified in the Sampling and Analysis Plan. Water levels will be measured in all monitoring wells at the site. Wells will be purged prior to sampling. Field parameters including temperature, pH, specific conductivity, dissolved oxygen, and oxidation reduction potential will be measured at all monitoring wells/stations where water samples will be collected. Field parameters will generally be measured during and at the conclusion of purging the monitoring wells. Water samples will be collected and shipped to Pace Analytical Laboratories (in Billings, Montana) for analysis of constituents shown in the SAP. The scope of analysis includes many of the constituents listed in Appendix I, 40 CFR Part 258 (July 1, 2008) in ARM 17.50.1306. The SAP also reflects DEQ approved changes to the monitoring schedule of specified monitoring wells. Five quality assurance/quality control (QA/QC) samples will be collected and prepared during the June 2022 assessment monitoring event. These will include the following: 1) three duplicate samples collected at selected monitoring sites and submitted for analysis of all constituents included in the SAP; 2) two trip blanks prepared by Pace Analytical Laboratories, shipped with the sample bottles, traveling with sample bottles in the field, and returned to the laboratory for analysis of VOCs; and 3) one decontamination blank collected from decontaminated, non-dedicated sampling equipment. Currently, pumps are used in wells LF-3, MW-4, MW-5, MW-6, MW-6B, and MW-8C. DocuSign Envelope ID: 7A066529-2DAA-4C73-AA3E-B963C8C31805 Task Order – 2021 to 2022 Groundwater and Methane Monitoring and Assessment Bozeman Landfill, Bozeman, Montana July 14, 2021 Page 4 of 6 TETRA TECH Task 500 Evaluate Groundwater Data and LFG System Flow Modification Data The 2018/2019 Remedial System Evaluation Report (dated March 11, 2020) identified increases in VOC concentrations in groundwater in well MW-17, including the appearance of methylene chloride above Montana groundwater protection standards for the first time since a single occurrence in 2015. This indicates the need to improve landfill gas capture in the southeast corner of the landfill. Our 2020-2021 Task Order included work to evaluate whether increasing air flow from nearby LFGES wells will reduce VOC concentrations in groundwater in the southeast corner of the landfill. This test is ongoing and the results of the collected data will be evaluated and used to develop recommendations for any future modifications to the LFG system in the southeast corner of the landfill. As part of the 2020-2021 Task Order, Tetra Tech evaluated the source and distribution of VOCs in groundwater. We see two possible scenarios: landfill gasses are not being fully captured by the LFGES (GW-20 was removed from the system to accommodate the convenience site), or landfill gasses are migrating offsite along the eastern property boundary, contacting groundwater (which allows phase transfer of VOCs), which subsequently migrate back onto the landfill site. Our analysis included investigating the potential to adjust flows in nearby LFGES wells to affect a vacuum across a larger portion of the southeast corner of the property and the possibility of installing a horizontal LFG well in the thin areas of refuse. To evaluate the possibility that VOCs are reaching groundwater upgradient of well MW-17, two new offsite monitoring wells were installed upgradient of MW-17 in June 2021. This FY 2021/2022 task will evaluate the well logs, groundwater flow directions and water quality data from these new wells to gain a better understanding of VOC migration in the southeast corner of the landfill. The data collected over the last two years will be used to identify if more groundwater monitoring wells are needed in the area to better understand the source of the VOCs observed in MW-17, if flow from existing LFG wells can be adjusted to increase the capture zone without pulling oxygen into the cell, and if new LFG or SVE wells are needed. The use of horizontal wells in areas of thin refuse will also be evaluated. Our recommendations will be submitted to the City in a technical memorandum, then based upon approval from the City, we will develop a scope of work for our recommendations. Task 600 Project Management, Statistical Analysis, and Reporting Project management will include progress reporting, scheduling of personnel, preparation/calibration of monitoring equipment/meters, supplies procurement, and other related activities; communication with City of Bozeman and DEQ; data management; administration/ invoicing; and task order preparation for 2022 monitoring activities. Following the completion of each groundwater monitoring event and receipt of laboratory results, DEQ will also be notified, in a letter report, as to which monitoring stations have regulatory exceedances of VOCs, metals, and/or inorganic constituents. Groundwater monitoring data will be entered into the project database and two reports will be prepared for the June 2021 and December 2021 groundwater monitoring events. Note that the data for the June 2021 report was collected under the Task Order for the 2020/2021 period. The June 2022 data collected under this Task Order will be compiled into a report under a subsequent Task Order for the 2022/2023 period. This is necessary due to the start of the new fiscal year being just weeks after the June groundwater monitoring event is conducted, which does not provide adequate time for the report to be completed before the end of the fiscal year DocuSign Envelope ID: 7A066529-2DAA-4C73-AA3E-B963C8C31805 Task Order – 2021 to 2022 Groundwater and Methane Monitoring and Assessment Bozeman Landfill, Bozeman, Montana July 14, 2021 Page 5 of 6 TETRA TECH covered by this Task Order. A statistical analysis of analytical constituents exceeding the groundwater protection or regulatory standards will be conducted in each of these groundwater monitoring events. The statistical analysis has been and will continue to be conducted in accordance with DEQ requirements (ARM 17.50.1305 (7-11)). In addition, a remediation evaluation technical memorandum will be prepared evaluating 2021 system data. The report will take a longer term look at the remediation system and develop a 5-year plan for system maintenance, equipment replacements and upgrades to assist the City in longer term budget planning. This report will be submitted to the City of Bozeman in early 2022 in time to develop recommendations for the City’s FY2023 budget setting process. It will also be submitted to DEQ, following City of Bozeman approval. PERIOD OF PERFORMANCE Tetra Tech’s anticipated schedule to complete the above described activities will be the following: Deliverable Completion Date Methane Perimeter Monitoring July 1, 2021 to June 30, 2022 September Groundwater Monitoring September 30, 2021 December Groundwater Monitoring December 31, 2021 March Groundwater Monitoring March 31, 2022 June Groundwater Monitoring June 30, 2022 June 2021 Groundwater Monitoring Report October 30, 2021 December 2020 Groundwater Monitoring Report April 31, 2022 2020 Remediation System Technical Memorandum March 31, 2022 Southeast Corner Evaluation Technical Memorandum November 1, 2021 COSTS Estimated costs to complete the foregoing scope of services are in shown below: Task Description Estimated Cost Task 100 Perimeter Methane Monitoring $6,342 Task 200 Quarterly Monitoring Events - March and September 2019’ $9,428 Task 300 December 2019 Groundwater Monitoring $21,485 Task 400 June 2020 Groundwater Monitoring $17,485 Task 500 Evaluate Groundwater Data and LFG System Flow Modification Data $5,000 Task 600 Project Management, Statistical Analysis, and Reporting $28,660 Total $88,400 Our costs will be on a time and materials basis. A detailed cost estimate can be provided upon request. DocuSign Envelope ID: 7A066529-2DAA-4C73-AA3E-B963C8C31805 Task Order – 2021 to 2022 Groundwater and Methane Monitoring and Assessment Bozeman Landfill, Bozeman, Montana July 14, 2021 Page 6 of 6 TETRA TECH SPECIAL CONDITIONS: Execution of this Task Order constitutes acceptance of all terms and conditions contained in Tetra Tech’s Professional Services Agreement with the City of Bozeman, dated April 15, 2014. CLIENT: CONSULTANT: City of Bozeman Tetra Tech By: By: Printed Name: Printed Name: Kirk A. Miller Its: Its: Senior Project Manager Date: Date: NOTICE OF CONFIDENTIALITY This Task Order (including attachments) contains information confidential to Tetra Tech, Inc., its subsidiaries, and subcontractors. It is intended only for City of Bozeman to consider Tetra Tech providing professional services at the Bozeman Landfill. Any other use is prohibited, without the prior written consent of Tetra Tech. DocuSign Envelope ID: 7A066529-2DAA-4C73-AA3E-B963C8C31805 7/28/2021 City Manager 7/28/2021 Jeff Mihelich